1. Field of the Invention
The invention concerns a device for the sterilization of fluid substances. More particularly, the invention relates to the sterilization of water or air, with the aid of a substance that develops a gas, having a disinfecting effect, upon the addition of an activator, preferably an aqueous solution.
2. Background of the Prior Art
In the field of the sterilization of medical instruments or, for example, in the preservation of food items, it is known to use synthetic plastic sheets that are permeable for gaseous substances. It is, therefore, important, particularly in the packaging of food items, to reduce the diffusion of oxygen in the direction of the food and the diffusion of carbon dioxide and aromatic gases from the packaged food items into the atmosphere. The diffusion of gases and of aromatic substances through synthetic plastic sheets is affected by numerous factors, the most important of which are the nature of the gases, the temperature and the pressure and the properties of the synthetic plastic sheet.
The diffusion of gases through synthetic plastic sheets may be interpreted in a manner similar to the diffusion of liquids, i.e. the gas is dissolved in the plastic material, migrates through it and emerges finally on the other side as the gas, whereupon it may enter in solution with a medium existing on that side.
Aroma tightness, which is highly important in relation to packaging technology, does not parallel the sealing properties of the sheet with respect to gases and is strongly dependent on the chemical structure of the aromatic substance. In the case of sheets which absorb humidity, such as for example, cellophane and polyamide, diffusion is accelerated by higher degrees of humidity. Diffusibility does not depend on the thickness of the sheet, but exclusively on the material. The thickness of the sheet merely represents a time factor, but has a strong influence on diffusion values.
The sterilization of drinking water or water in bathing facilities, at the present time, is effected overwhelmingly by means of chlorine gas from gas bottles. The production of chlorine gas, the filling of the gas into bottles, the transportation, storage and discharge during sterilization are all expensive and potentially dangerous steps. Thus, they are normally handled by skilled persons only, and such handling is complicated. Accordingly, extremely accurate dosages must be maintained particularly during sterilization in order to prevent danger to persons. In view of this fact, attempts have already been made to use chlorine gas producing substances. However, the application of substances of this type has the significant disadvantage that following the release of the gas, the residues of the chemical compounds remain in the water to be sterilized so that undesirable or even toxic effects cannot be excluded with certainty. This means that, for example, in the sterilization of water in swimming pools, persons swimming therein may come into contact with such residues, whereby even internal contacts cannot be excluded.
Since the substances releasing the gas are produced industrially, they may contain impurities. Therefore, even when the main residue remaining is harmless, detrimental or undesirable, contamination may take place from impurities as the products are not prepared in an analytically pure manner.
West German Offenlegungsschrift No. 17 67 635 discloses a chlorine filter, which is intended specifically for swimming pools. Therein the chlorine tablets or chlorine granules are first packaged in the proper doses in a synthetic plastic bag which is perforated over its surface or part of its surface. For transportation or storage of the chlorine tablets, this perforated plastic bag is packed in a second synthetic plastic bag and sealed in an absolutely tight manner, so that no chlorine gas may escape. Plastic bags provided with perforations, however, are incapable of retaining impurities of the chlorine gas releasing substances.
West German Offenlegungsschrift No. 16 42 474 further discloses a process and a device for the regeneration of water with gaseous media, wherein the gas, for example carbon dioxide, is to be mixed with the liquid by means of diffusion. The process is realized by means of an apparatus consisting of a container to be partially filled with gas and intended to establish direct contact between the gas and the liquid, thus creating favorable conditions for diffusion. In order to restrict the diffusion to a certain level and to maintain a constant supply of the gas in the container, partitions or sleeves permeable to the gas are provided. These means therefore serve to slow the mixing process in order to maintain a continuous action. The diffusion process in the above Offenlegungsschrift does not take place as described across plastic membranes but during free contact between gas and water.